The accuracy of laser displacement measurement based on triangulation is affected not only by optical source, detector and mechanical construction, but also have relation with measured surface features such as luster, material, roughness, inclination and environment. Some researchers have presented some methods to improve the measurement accuracy, which based on the same surface features. In this paper the scattered light field on the measured surface is analyzed with random walk theory. The relations of scattered light intensity and scattered light detected angle on different roughness surface are shown. Because the scattered light detected angle of sensor we made is between the 15°to 25°, the value of scattered light angle is assumed to be 20°, the maximum change of scattered light intensity on three different roughness surface is roughly 300% through the simulation. These model and results are helpful to the optimal design of the laser displacement sensor and improvement of measurement accuracy.